This invention relates to underwires used in foundation garments such as brassieres.
Underwires are employed to provide shape and support to brassieres, corsets and other similar foundation undergarments. They are typically rigid, flat steel members having a U-shaped configuration, or are formed from a hard, molded or extruded engineering plastic having some inherent shape and curvature.
Underwires used in the manufacture of brassieres and the like have been provided with a plastic or polymeric tip at either end. Examples of the construction and the assembly of underwires having such tips are disclosed in U.S. Pat. No. 4,133,316.
The underwire is maintained in a sleeve or casing that is formed below the breast cup of the brassiere and that is necessarily made from a soft woven or knitted fabric. In order to prevent one or both ends of the metal or polymeric underwire from penetrating the fabric casing and/or pressing uncomfortably through the garment into the wearer, it has long been the practice to provide the free ends of the underwire with a tip.
The polymeric tip can be in the form of a molten thermoplastic material into which the underwire is dipped and then removed and allowed to cool and harden into a generally spherical shape. Alternatively, the plastic material can be further shaped while in a pliable state in order to create contours that will easily pass through the retaining casing when it is assembled to the garment and that will fit comfortably against the wearer. An improved cushion tip in which a relatively soft and pliable polymeric material is molded directly on to the free end of the underwire is described in U.S. Pat. No. 5,830,040, the disclosure of which is incorporated herein by reference.
In a second embodiment known to the art, the tip is produced separately from a polymeric material and then fitted using appropriate retaining means to the end of the underwire. In a more recent advance in the art, the separate polymeric tips have been produced using a material that is more pliable and has the feel of an apparently xe2x80x9csofterxe2x80x9d terminus to the wearer of the garment.
Despite the advance in the art of providing a more pliable tip having a softer feel, problems are still known to exist. For example, when the wearer assumes certain positions in which the torso is turned and/or twisted, as in bending over to pick up something from a position to the wearer""s right or left side, the tip of the underwire which lies beneath the arm tends to exert an extreme pressure against the end of the fabric casing. Depending upon the age, condition and type of fabric used in the casing, the tip can puncture the casing. This condition is not readily reparable and the garment may have to be discarded. In addition, the protruding tip may contact the wearer""s flesh causing extreme discomfort.
Even if the tip of the underwire does not penetrate the casing, the turning and twisting and/or bending of the torso can still cause the tip of the underwire to press into the flesh beneath the wearer""s arm and produce discomfort that spans the spectrum from merely uncomfortable to painful. Periodic physiological changes are also experienced by some women in association with their menstrual cycle, as well as during pregnancy, can results in discomfort at time.
Variations in body types and anatomical differences can also result in discomfort among some women even when the brassiere is of the xe2x80x9ccorrectxe2x80x9d size. some women also find that a particular style or design of brassiere is not as comfortable as others because the tip of the underwire produces an undesired pressure.
Yet an other recognized problem is a change that occurs when the garment is laundered, particularly with respect to shrinkage of the fabric pocket or tube that retains the underwire in place. Such shrinkage of the fabric of the casing and/or of the brassiere itself results in a continuous internal force applied by the underwire tip against the closed end of the casing and premature wear and failure of the casing. Once the underwire has broken through, the garment is deemed to be unwearable long before its otherwise useful life is reached.
It is therefore an object of the present invention to provide an improved tip assembly and construction for an underwire which is more responsive to pressures and forces that are applied during the physical activity of the wearer to thereby reduce or entirely avoid the application of excessive concentrated force to the casing containing the underwire and to the wearer.
It is also an object of the invention to provide an underwire having a resiliently mounted tip that is relatively inexpensive to manufacture and assemble and which is reliable in its mode of operation and rugged in construction.
Yet another object of the invention is to provide a resiliently mounted tip assembly and method of construction for an underwire that is adapted for use with both metal and polymeric underwires and that can be produced from a variety of materials in various shapes and sizes to accommodate the requirements of the trade.
The above objects and other advantages are realized in the improved underwire which comprehends the resilient mounting of a polymeric tip on at least one end of a garment-supporting underwire. In a first preferred embodiment, the tip is separately formed, i.e., by molding and/or machining the tip from a polymeric material having a composition commonly used for such purposes. The tip is resiliently mounted on a free end of the underwire for sliding movement within a predetermined range. The range of movement of the tip can be determined by the cooperative engagement of mounting means on the free end of the underwire with the tip.
In one aspect of this embodiment, a compression spring is mounted between a retaining shoulder formed on the underwire and the proximal end of the tip. When a force is applied to the distal end of the tip, the tip slides along the longitudinal axis of the underwire to compress the spring. When the force is removed or lessened, the spring urges the tip to return to its original position.
In another aspect of this embodiment, the tip is again mounted on the underwire in longitudinal sliding relation. A spring which can act in both extension and compression is affixed at one of its ends to a point of attachment on the free end of the underwire and at its opposite end to a point of attachment on the slidable tip. As in the earlier-described embodiment, when a longitudinal force vector is applied to the distal end of the tip, the tip moves along the underwire and is opposed by the resisting force of the spring in compression. When the compressive force is removed or lessened, the tip returns to its original position.
In this second aspect of the invention, it is contemplated that the distal end of the tip is sewn or otherwise secured in position at the end of the casing. Thus, when the wearer""s motion is such that the opposite end and/or intermediate portion of the underwire is subjected to a force in the opposite direction, i.e., away from the secured resiliently-mounted tip, the retaining spring expands until such force is reduced or discontinued, after which the extended spring returns to its neutral position and brings with it the underwire. This construction has the advantage of eliminating movement of the tip within the casing, which can lead to excessive wear of the fabric casing in the vicinity of the tip and to premature failure of the casing.
The invention also comprehends an underwire in which at least one, but preferably a plurality of resilient elements are included in, and form an integral part of the underwire. The one or more resilient members can be displaced from the point of attachment of the tips, for example, at three spaced apart locations. The one or more resilient members can take the form of coiled metal expansion and/or compression springs the ends of which are molded into and retained by the adjacent sections of the underwire, e.g., a molded plastic composition of a type known to the prior art. Alternatively, a metal spring can be incorporated by welding to a section of a metal underwire. In yet another alternative construction, the one or more resilient members are formed integrally with the underwire, as by molding of an underwire formed of plastic.
In this latter embodiment, the underwire is produced with at least one resilient portion that is integrally formed, e.g., by molding, stamping and/or machining processes known to the art. In a particularly preferred aspect of this embodiment, the underwire is produced from a polymeric material and is provided with a plurality of generally V-shaped elements which are joined to form a portion having a zig-zag or accordion configuration. This configuration responds to compressive and extensive forces applied longitudinally to the underwire providing a resistance and reflexive force that is analogous to that of a spring. This resilient portion of the underwire is preferably positioned adjacent a free end which is configured to receive a separate tip in fixed relation. Alternatively, the tip can be integrally molded with the underwire body. When a compressive force is applied to the distal end of the tip, the integral resilient portion of the underwire is compressed proportionately. Just as a steel spring has an associated spring constant value, a similar or comparable value can analogously be calculated for various configurations of the zig-zag elements forming the integral resilient portion of the underwire. Other alternative and preferred configurations of flexible longitudinal elements integrally formed in the underwire are described in more detail below.
The range of movement of the tip with respect to the underwire is not critcal. The travel of the tip can be from about 0.12 to about 0.5 inches, or from about 2 mm to about 13 mm. The range can be varied based upon the size and type or style of the garment; whether one or both ends of the underwire are provided with resiliently mounted tips, and other factors that will be apparent to one of ordinary skill in the art.
The tip is preferably formed from a polymeric material that has sufficient resiliency to deflect when subjected to a lateral force and return to its original form. The polymer selected should have sufficient elasticity to permit the tip to be passed over a contoured retaining flange or pin formed on the free end of the underwire and then return to its original configuration. The polymeric material chosen for the tip also must have sufficient tensile strength to resist deformation at its points of attachment to the underwire and the end of the spring in the embodiment described above. Suitable polymers can be selected from the class of thermoplastic polyoletin elastomers. Products sold in the United States by DuPont Dow under the trademark ENGAGE(copyright), 8401 and 8402, can be utilized.
The underwire can be fabricated from stainless steel, or steel that has been galvanized or otherwise coated. Aluminum and aluminum alloys, copper and copper alloys, steel alloys, and other types of metal can be used without limitation.
As is also known to the art, the underwire can be fabricated from various polymeric materials and engineering plastics. Suitable polymers, copolymers and blends used for molding, extruding and machining of underwires can include nylon, polyethylene, butadiene/styrene, acrylonitile/butadiene/styrene, polycarbonates, polyvinyl chlonde, and others. Desired physical properties can be provided and enhanced by reinforcing the polymers by addition of glass and carbon fibers to the liquid resins. Polymeirc or plastic underwire bodies can be of any cross-sectional configuration and dimension that is known to be useful in the art, and such features are not critical to the method or apparatus of the invention.
In all of these embodiments, including those last described above, the overall length of the underwire is reduced in response to a compressive force resulting from any of a change in the wearer""s position, the wearer""s anatomy, shrinkage of the garment, or the application of an excessive strain during mechanical washing. Thus, the above objects are achieved and other advantages are realized by the construction and operation of the improved underwire of the invention.